FreeBSD Manual Pages

VMSTAT(8) BSD System Manager's Manual VMSTAT(8)
NAMEvmstat -- report virtual memory statistics
SYNOPSISvmstat [--libxo] [-afHhimoPsz] [-Mcore [-Nsystem]] [-ccount] [-ndevs]
[-ptype,if,pass] [-wwait] [disks...] [wait [count]]
DESCRIPTION
The vmstat utility reports certain kernel statistics kept about process,
virtual memory, disk, trap and cpu activity.
If the -M option is not specified, information is obtained from the cur-
rently running kernel via the sysctl(3) interface. Otherwise, informa-
tion is read from the specified core file, using the name list from the
specified kernel image (or from the default image).
The options are as follows:
--libxo
Generate output via libxo(3) in a selection of different human
and machine readable formats. See xo_parse_args(3) for details
on command line arguments.
-a When used with -i, include statistics about interrupts that have
never been generated.
-c Repeat the display count times. The first display is for the
time since a reboot and each subsequent report is for the time
period since the last display. If no repeat count is specified,
and -w is specified, the default is infinity, otherwise the de-
fault is one.
-f Report on the number fork(2), vfork(2) and rfork(2) system calls
since system startup, and the number of pages of virtual memory
involved in each.
-h Changes memory columns into more easily human readable form. The
default if standard output is a terminal device.
-H Changes memory columns into straight numbers. The default if
standard output is not a terminal device (such as a script).
-i Report on the number of interrupts taken by each device since
system startup.
-M Extract values associated with the name list from the specified
core.
-N If -M is also specified, extract the name list from the specified
system instead of the default, which is the kernel image the sys-
tem has booted from.
-m Report on the usage of kernel dynamic memory allocated using
malloc(9) by type.
-n Change the maximum number of disks to display from the default of
2.
-o Display a list of virtual memory objects in the system and the
resident memory used by each object.
-P Report per-cpu system/user/idle cpu statistics.
-p Specify which types of devices to display. There are three dif-
ferent categories of devices:
device type:
da Direct Access devices
sa Sequential Access devices
printer Printers
proc Processor devices
worm Write Once Read Multiple devices
cd CD devices
scanner Scanner devices
optical Optical Memory devices
changer Medium Changer devices
comm Communication devices
array Storage Array devices
enclosure Enclosure Services devices
floppy Floppy devices
interface:
IDE Integrated Drive Electronics devices
SCSI Small Computer System Interface devices
other Any other device interface
passthrough:
pass Passthrough devices
The user must specify at least one device type, and may specify
at most one device type from each category. Multiple device
types in a single device type statement must be separated by com-
mas.
Any number of -p arguments may be specified on the command line.
All -p arguments are ORed together to form a matching expression
against which all devices in the system are compared. Any device
that fully matches any -p argument will be included in the vmstat
output, up to two devices, or the maximum number of devices spec-
ified by the user.
-s Display the contents of the sum structure, giving the total num-
ber of several kinds of paging related events which have occurred
since system startup.
-w Pause wait seconds between each display. If no repeat wait in-
terval is specified, the default is 1 second. The vmstat command
will accept and honor a non-integer number of seconds.
-z Report on memory used by the kernel zone allocator, uma(9), by
zone.
The wait and count arguments may be given after their respective flags at
any point on the command line before the disks argument(s), or without
their flags, as the final argument(s). The latter form is accepted for
backwards compatibility, but it is preferred to use the forms with -w and
-c to avoid ambiguity.
By default, vmstat displays the following information:
procs Information about the number of threads in various states:
r running or in run queue
b blocked for resources (i/o, paging, etc.)
w swapped out
memory Information about the usage of virtual and real memory.
Mapped virtual memory is a sum of all of the virtual pages be-
longing to mapped virtual memory objects. Note that the entire
memory object's size is considered mapped even if only a subset
of the object's pages are currently mapped. This statistic is
not related to the active page queue which is used to track real
memory.
avm mapped virtual memory (previously called active in vmstat
output)
fre size of the free list
page Information about page faults and paging activity. These are
given in units per second.
flt total number of page faults
re page reclaims (simulating reference bits)
pi pages paged in
po pages paged out
fr pages freed
sr pages scanned by page daemon
disks Disk operations per second (this field is system dependent).
Typically paging will be split across the available drives. The
header of the field is the first two characters of the disk name
and the unit number. If more than two disk drives are configured
in the system, vmstat displays only the first two drives, unless
the user specifies the -n argument to increase the number of
drives displayed. This will probably cause the display to exceed
80 columns, however. To force vmstat to display specific drives,
their names may be supplied on the command line. The vmstat
utility defaults to show disks first, and then various other ran-
dom devices in the system to add up to two devices, if there are
that many devices in the system. If devices are specified on the
command line, or if a device type matching pattern is specified
(see above), vmstat will only display the given devices or the
devices matching the pattern, and will not randomly select other
devices in the system.
faults Trap/interrupt rates per second.
in device interrupts (including clock interrupts)
sy system calls
cs cpu context switches
cpu Breakdown of percentage usage of CPU time.
us user time for normal and low priority processes
sy system and interrupt time
id cpu idle
FILES
/boot/kernel/kernel default kernel namelist
/dev/kmem default memory file
EXAMPLES
The command:
vmstat -w 5
will print what the system is doing every five seconds.
The command:
vmstat -p da -p cd -w 1
will tell vmstat to select the first two direct access or CDROM devices
and display statistics on those devices, as well as other systems statis-
tics every second.
SEE ALSOfstat(1), netstat(1), nfsstat(1), ps(1), systat(1), libmemstat(3),
libxo(3), xo_parse_args(3), gstat(8), iostat(8), pstat(8), sysctl(8),
malloc(9), uma(9)
The sections starting with ``Interpreting system activity'' in InstallingandOperating4.3BSD.
BUGS
The -c and -w options are only available with the default output.
BSD January 18, 2018 BSD